having problems with a FX4 filter

[FishHobby99]

I purchased a used 125 G that came with two Fluval Fx4 canister filters. The system appears to be brand new & is just under 2 years old. One filter is up & running . Seller said both good until he disassembled the setup & says he installed new impellers a a gasket ~3 months ago, adding they should last a year and he is totally mystified as to why one isn’t working here. Everything is properly connected. I texted him photos. He said go ahead and buy another impeller at Amazon which should arrive tomorrow. Amazon also sells the motor for $84. I have never owned a canister filter before & don’t see what it could be other than the impeller or motor, since they wre both properly connected. We even used an air compresser to make sure the hoses weren’t clogged.

The one by the power strip isn’t working. The other is.

 

[Guyb93]

Doesn’t the filter purge the air on start up ?
Have you tried swapping the tops of the filter around to see if it works then ?
Silly question but are the in and out pipes on the correct tap and is the flow restriction fully open ?
Other than that I wouldn’t buy a new motor it’s not worth it really you can get a second hand one for roughly the same price as a motor
You will be ok with only running one also o ran one fx4 on a 125g for over a year before upgrading to a fx6

 

[Colin_T]

Impellors and o-rings should last for years. You can test the impellor by holding the magnet and turning the plastic blades with your finger. If the plastic blades go round and round and don't stop while you are holding the magnet, then it is broken and you can either replace it or superglue the plastic blades to the magnet.

O-rings can be lubed up with some Vaseline when you clean the filter. Just smear a thin layer on the o-ring and it should last for years.

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Take the motor off the filter case and disconnect the hoses. Plug the motor into a power socket and turn it on for a few seconds. See if the impellor is spinning. If it is, that's a good sign and suggests the problem is in the filter. This could be air, blocked or kinked hoses, or something else.

I wouldn't be buying any replacement parts until you try other things. Most filters are pretty good and don't die after 2 years.

 

[Wills]

Great advice here already - when you say its not working do you mean its dead when you plug it in?

 

[FishHobby99]

Doesn’t the filter purge the air on start up ?
Have you tried swapping the tops of the filter around to see if it works then ?
Silly question but are the in and out pipes on the correct tap and is the flow restriction fully open ?
Other than that I wouldn’t buy a new motor it’s not worth it really you can get a second hand one for roughly the same price as a motor
You will be ok with only running one also o ran one fx4 on a 125g for over a year before upgrading to a fx6

Yes, it did purge air. Not sure what you mean by swapping the tops of the filter. Due to the stand pipe, the top can only go on one way. Or did you mean swapping between the two different filters? Yes, the in & out hoses are open & were correctly installed. I saw a few guys setting them up on YouTube.
These filters sell for $300 new. I saw a used one snapped up for $150 in a local Facebook group. I have no idea if this is typical or not. And yes! The single working one would provide adequate filtration.

 

[FishHobby99]

Impellors and o-rings should last for years. You can test the impellor by holding the magnet and turning the plastic blades with your finger. If the plastic blades go round and round and don't stop while you are holding the magnet, then it is broken and you can either replace it or superglue the plastic blades to the magnet.

O-rings can be lubed up with some Vaseline when you clean the filter. Just smear a thin layer on the o-ring and it should last for years.

------------------
Take the motor off the filter case and disconnect the hoses. Plug the motor into a power socket and turn it on for a few seconds. See if the impellor is spinning. If it is, that's a good sign and suggests the problem is in the filter. This could be air, blocked or kinked hoses, or something else.

I wouldn't be buying any replacement parts until you try other things. Most filters are pretty good and don't die after 2 years.

I did plug the motor in and the impeller rotated roughly. I did not know enough to try the first test you mention. I texted the seller and he said plugging it in is not a good test, because it is designed to run submerged. idk. This guy said the impellers last a year & he replaced it 3 months ago and he is thoroughly mystified as to why the one isn’t working for me. He seemed like an honest enough chap. Works in a pet shop and breeds birds which are sold to numerous pet shops. Had a fantastic group of a aviaries and birds. Said he prefers the birds to the fish.

 

[FishHobby99]

Great advice here already - when you say its not working do you mean its dead when you plug it in?

I mean that it does not uptake water or expel it through the hose jets. I can feel a jerky vibration when I touch the motor for a few minutes and then it stops. A few weak jets of water are expelled for this brief time. When the motor stops, I turn it off. This process repeats itself. Someone suggested I make sure the pipe stand is properly seated, so I removed the top. It was seated right & I ran a pipe cleaner through the bottom to make sure nothing was clogged. Got the same brief motor activation & then it stopped again.

 

[Wills]

I mean that it does not uptake water or expel it through the hose jets. I can feel a jerky vibration when I touch the motor for a few minutes and then it stops. A few weak jets of water are expelled for this brief time. When the motor stops, I turn it off. This process repeats itself. Someone suggested I make sure the pipe stand is properly seated, so I removed the top. It was seated right & I ran a pipe cleaner through the bottom to make sure nothing was clogged. Got the same brief motor activation & then it stopped again.

Its not the 2 minute air release is it? Plug the filter in let it get to the point where it does nothing and then wait for a few minutes - if its not come back on after 5 mins definitely a problem but you might find it runs for a few mins then it cuts out for a few mins then it comes back, its to help dispel the air after its been turned off. These filters also turn off for a few minutes each day to let out air too.

Wills

 

[FishHobby99]

Its not the 2 minute air release is it? Plug the filter in let it get to the point where it does nothing and then wait for a few minutes - if its not come back on after 5 mins definitely a problem but you might find it runs for a few mins then it cuts out for a few mins then it comes back, its to help dispel the air after its been turned off. These filters also turn off for a few minutes each day to let out air too.

Wills

Think I know what you’re saying & that‘s probably not the issue. I read about the 2 min release etc & saw videos & went through that process. All went well on the other filter. But maybe we should give it another go. the husband is at the gym now. I’ll have him go through all of your replies later. He’s a very smart software engineer who rebuilds vintage cars. He is likely to pick up on something you guys said that went over my head. Thanks so much!

 

[Wills]

Think I know what you’re saying & that‘s probably not the issue. I read about the 2 min release etc & saw videos & went through that process. All went well on the other filter. But maybe we should give it another go. the husband is at the gym now. I’ll have him go through all of your replies later. He’s a very smart software engineer who rebuilds vintage cars. He is likely to pick up on something you guys said that went over my head. Thanks so much!

Let us know how it goes - the first time I plugged an FX filter in and it turned of after 2 mins I was running round panicking like mad haha!

 

[Colin_T]

Have you compared the motors and impellors from both filters?
Basically take the motors off both filters and put them next to each other and make sure they have the same bits in them.

Check to make sure the faulty motor has all the parts holding the impellor in place. Maybe even swap the impellor over and see what happens.

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If the guy that sold you the filters is correct and the impellors need replacing once a year, there is something seriously wrong with the design. I have had numerous power filters and power heads all driven by impellors and the impellors last for years.

If these impellors only last a year or so, you might want to contact the company and hassle them about the impellors. Don't tell you bought the units secondhand, just say you have a couple of filters and they seem to go through a lot of impellors. Any ideas why?

 

[FranciscoB]

Impellers (not impellOrs) in Fluval FX filters (FX 4, 5, 6) do NOT just last a year. I have 2 FX6s, one since 2017, the other since 2019. I have never changed an impeller or had to buy a rebuild kit, and both filters continue to work beautifully.
I am not sure what is wrong, and what I suggested (in another forum) did not solve the problem. I suggest two things:
1) Disassemble the motor unit and reassemble. Very possibly it is not set correctly, a couple of small details are possible causes, which it is possible even for an experienced owner.
2) Take the filter back to the original owner and have him try (not that I think he will know better, but why not since he is the source and as you said, seems like an honest guy).

It is not true that FX filter rebuild kits are so expensive as to not be worth it:
- Rebuild kit for FX4 ($ 36.39) - https://kensfish.com/products/fluval-fx4-service-kit?_pos=2&_sid=42be7fba4&_ss=r
- New motor for FX4 ($ 69) - https://kensfish.com/products/fluval-fx4-filter-motor-unit?_pos=4&_sid=42be7fba4&_ss=r
- New impeller for FX4 ($ 26.19) - https://kensfish.com/products/fluval-fx4-impeller-assembly?_pos=1&_sid=42be7fba4&_ss=r
- Complete brand new FX4 ($ 299.99) - https://kensfish.com/products/fluval-fx4-canister-filter?_pos=3&_sid=42be7fba4&_ss=r

One additional item: The motor is a sealed unit with just about nothing to break. Thus, if the impeller appears to be sound, and the filter hums, the issue is almost certainly a small goofy detail of putting it together improperly. I would be very surprised otherwise.

Depending on stocking and maintenance routines, an FX4 may not satisfy as the only filter in a 125gal. Both of my 6foot tanks (125g, and 115g) have an FX6 + 1 Aquaclear 110 + 1 Penguin 350. Of course, each user sees things differently....
Good luck!

 

[FishHobby99]

Have you compared the motors and impellors from both filters?
Basically take the motors off both filters and put them next to each other and make sure they have the same bits in them.

Check to make sure the faulty motor has all the parts holding the impellor in place. Maybe even swap the impellor over and see what happens.

-------------------
If the guy that sold you the filters is correct and the impellors need replacing once a year, there is something seriously wrong with the design. I have had numerous power filters and power heads all driven by impellors and the impellors last for years.

If these impellors only last a year or so, you might want to contact the company and hassle them about the impellors. Don't tell you bought the units secondhand, just say you have a couple of filters and they seem to go through a lot of impellors. Any ideas why?

I am also having a terrible time with my Fluval Aquaclears. I have several 70s and 110s. The media, especially the sponge, floats up so that the bio cylinders are out of the water. This is a common problem. I see many posts on Redditt etc. Some remove 1 of the 3 inserts. Some try weighting down the baskets with pebbles. I did this & they still float. I am about to replace their bricks of white foam with the type of black foam I use in my sump filter. .

That’s a great idea to visually compare them.

 

[FishHobby99]

Impellers (not impellOrs) in Fluval FX filters (FX 4, 5, 6) do NOT just last a year. I have 2 FX6s, one since 2017, the other since 2019. I have never changed an impeller or had to buy a rebuild kit, and both filters continue to work beautifully.
I am not sure what is wrong, and what I suggested (in another forum) did not solve the problem. I suggest two things:
1) Disassemble the motor unit and reassemble. Very possibly it is not set correctly, a couple of small details are possible causes, which it is possible even for an experienced owner.
2) Take the filter back to the original owner and have him try (not that I think he will know better, but why not since he is the source and as you said, seems like an honest guy).

It is not true that FX filter rebuild kits are so expensive as to not be worth it:
- Rebuild kit for FX4 ($ 36.39) - https://kensfish.com/products/fluval-fx4-service-kit?_pos=2&_sid=42be7fba4&_ss=r
- New motor for FX4 ($ 69) - https://kensfish.com/products/fluval-fx4-filter-motor-unit?_pos=4&_sid=42be7fba4&_ss=r
- New impeller for FX4 ($ 26.19) - https://kensfish.com/products/fluval-fx4-impeller-assembly?_pos=1&_sid=42be7fba4&_ss=r
- Complete brand new FX4 ($ 299.99) - https://kensfish.com/products/fluval-fx4-canister-filter?_pos=3&_sid=42be7fba4&_ss=r

One additional item: The motor is a sealed unit with just about nothing to break. Thus, if the impeller appears to be sound, and the filter hums, the issue is almost certainly a small goofy detail of putting it together improperly. I would be very surprised otherwise.

Depending on stocking and maintenance routines, an FX4 may not satisfy as the only filter in a 125gal. Both of my 6foot tanks (125g, and 115g) have an FX6 + 1 Aquaclear 110 + 1 Penguin 350. Of course, each user sees things differently....
Good luck!

The Fluval gods have smiled upon you. Glad to hear they can live long and prosper. Thanks for the price list links. The motor is significantly cheaper than at Amazon & the shipping would be free. The impeller due tomorrow is about the same. I have not compared other prices.

By disassembling the motor do you mean removing the impeller? That will have to be done tomorrow when the new one arrives.

The previous owner lives a few hours a way. He does not have a tank to set it up in & even so, somethings are too much to ask, including asking him to come here. He’s a busy man.

I tend to over filter and have 2 AquaClear 110s and a 70 on my 90 G. The other 90 G has a nice 20 G sump tank.

Your tanks are spectacular! . Who lives there?

thanks for your useful reply. Much appreciated!

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[Fishmanic]

Impellers (not impellOrs) in Fluval FX filters (FX 4, 5, 6) do NOT just last a year. I have 2 FX6s, one since 2017, the other since 2019. I have never changed an impeller or had to buy a rebuild kit, and both filters continue to work beautifully.
I am not sure what is wrong, and what I suggested (in another forum) did not solve the problem. I suggest two things:
1) Disassemble the motor unit and reassemble. Very possibly it is not set correctly, a couple of small details are possible causes, which it is possible even for an experienced owner.
2) Take the filter back to the original owner and have him try (not that I think he will know better, but why not since he is the source and as you said, seems like an honest guy).

It is not true that FX filter rebuild kits are so expensive as to not be worth it:
- Rebuild kit for FX4 ($ 36.39) - https://kensfish.com/products/fluval-fx4-service-kit?_pos=2&_sid=42be7fba4&_ss=r
- New motor for FX4 ($ 69) - https://kensfish.com/products/fluval-fx4-filter-motor-unit?_pos=4&_sid=42be7fba4&_ss=r
- New impeller for FX4 ($ 26.19) - https://kensfish.com/products/fluval-fx4-impeller-assembly?_pos=1&_sid=42be7fba4&_ss=r
- Complete brand new FX4 ($ 299.99) - https://kensfish.com/products/fluval-fx4-canister-filter?_pos=3&_sid=42be7fba4&_ss=r

One additional item: The motor is a sealed unit with just about nothing to break. Thus, if the impeller appears to be sound, and the filter hums, the issue is almost certainly a small goofy detail of putting it together improperly. I would be very surprised otherwise.

Depending on stocking and maintenance routines, an FX4 may not satisfy as the only filter in a 125gal. Both of my 6foot tanks (125g, and 115g) have an FX6 + 1 Aquaclear 110 + 1 Penguin 350. Of course, each user sees things differently....
Good luck!

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@FranciscoB
You’ve been holding out on us by not entering those tanks in our Tank of the Month contests. Our August contest will feature tanks sized at 31 gallons and larger. You should enter one of your tanks in the contest.